Coke Oven With Optimized Control and Method of Control

ABSTRACT

This invention relates to a coking oven in flat-type construction, a non-recovery or heat-recovery coking oven, which has at least one measuring apparatus for measuring the concentration of gasous constituents of the coke oven retort, the coke oven hearth and/or the off gas duct, and in which, on the basis of these data, a process control computer determines and regulates the optimal supply of primary and/or secondary air. Also embraced by the invention is a coking method employing a coking oven of this kind.

This invention relates to a coke oven built in flat-type construction,i.e. a so-called non-recovery or heat-recovery coke oven consisting ofat least one measuring device to measure the concentration of gasconstituents in the coke oven chamber, coke oven sole and/or waste gaschannel, and wherein the optimal supply of primary and/or secondary airis determined and controlled via a process computer on the basis of thisdata. This invention also covers a cokemaking process utilizing a cokeoven of this type.

Heating of heat-recovery ovens is usually performed by combustion of gasevolving on cokemaking and/or by burning the portions of light-volatilematter of coal to be carbonized. Combustion is controlled in such amanner that part of the gas above the coal charge burns off with primaryair in the oven chamber. This partly burnt gas is fed through gaschannels that are also designated as “downcomers” to the oven sole andcompletely burnt there by the addition of further combustion air, whichis called secondary air.

In this way, heat is directly supplied from the top and indirectly fromthe bottom to the coal charge, thus taking a positive impact on thecoking rate and, thereby, on the performance rate of coke ovens. Toexecute the method it is required to exactly rate and variably controlthe supplied primary and secondary air throughout the coking time thatmay take up to 96 hours. Heat-recovery and non-recovery coke ovens inflat-type construction are widely described in prior art disclosures.For example, reference is taken to U.S. Pat. No. 4,344,820, U.S. Pat.No. 4,287,024, U.S. Pat. No. 5,114,542, GB 1 555 400 or CA 2 052 177 C.

According to the conventional state of the art in technology, primaryair is sucked in from the atmosphere through ports in the doors.Secondary air is sucked in through ports near to ground and conductedthrough channels into the heating flues which mainly extend horizontallyunder the coke oven chamber. The ports for primary and secondary air areeither opened permanently or provided with flaps designed to adjust theamount of air to be aspirated.

As the coke oven batteries are very extensive, and since usually a veryhigh temperature prevails therein and because a serious development ofdust is encountered, only manually adjustable venting flaps aredisclosed in prior art technology. U.S. Pat. No. 5,928,476 describessuch a coke oven battery, wherein three manually operable ports areprovided in each coke oven door, in which or in front of which one plateor disk each adapted to the port cross-section and supported at acentral axle is arranged. These port flaps can be varied in theirposition manually through levers.

The German patent DE102005055483.0-24 of the applicant discloses acentral adjusting element that permits a continuous control of primaryand secondary air.

In practice, however, it became evident that varying coal qualities dueto different coal crushing degrees, coal moisture or inert portions,etc. were difficult to master with prior art coke ovens and thatunnecessarily long coking times had to be planned to attain high cokequality.

Now, therefore, it is the object of this invention to remedy thedescribed deficiencies in an economic manner and to assure an optimizedsupply of primary air and/or secondary air in order to improve coke ovenperformance rate and, thereby, coking time, too.

This invention solves this task by providing a coke oven built inflat-type construction, i.e. a so-called non-recovery or heat-recoverycoke oven consisting of a coke oven chamber and a coke oven soleconsisting of channels, with the coke oven chamber and the coke ovensole being connected to each other via gas channels, and wherein openingports for the supply of primary air and one or more opening port(s) orchannel(s) for the supply of secondary air into the coke oven sole areprovided in the oven wall or in the oven door, and wherein shutoffdevices are arranged in front of the opening ports or in the linesconducing to these opening ports.

Accordingly,

-   -   at least one measuring device to measure the concentration of        gas constituents in the coke oven chamber, coke oven sole and/or        gas channels is linked to the coke oven, and    -   this measuring device in turn is connected to a computer unit in        such a way that this computer unit can receive data and measured        results from the measuring device, and    -   the computer unit is linked to one or more adjusting device(s)        of the shutoff devices, with said shutoff devices representing        valves, flaps, slide gates, or the like.

An improved variant resides in arranging a temperature measuring devicein the coke oven sole or in the waste gas channel of the coke oven,wherein said temperature measuring device is also connected to thecomputer unit in such a way that it can receive data and measuringresults from the temperature measuring device.

The measuring devices ideally represent analysers to measure hydrogen,nitrogen, carbon monoxide or carbon dioxide, said measuring devicesbeing connected via a line to the coke oven chamber. The concentrationof these main constituents or of one of these main constituentscorrelates very well with the coking state of the coke cake.

Above all it is hydrogen burning off as the last coal constituent thatis an ideal indicator to indicate the end of coking time. Hence, withthe coke oven embodying this invention, it is possible to control thecokemaking process in such a manner that the end of the coking time isachieved, in a way, concurrently to achieving 0% by vol. of H₂. For ifH₂ has burnt off prematurely, this leads to an increased combustionand/or incineration of coke valuables which represents an economicdrawback.

In another variant of this invention, the measuring device is a lambdaprobe arranged in the coke oven sole or in the waste gas channel todetermine the content of oxygen. By means of the lambda probe, and by afeedback with the control of secondary air, it can be assured that acomplete combustion will always occur in the coke oven sole without toodrastic a drop in temperature which would lead to a prolongation incoking time.

With an advanced variant of this invention, at least one analyzer forthe determination of hydrogen, nitrogen, carbon monoxide or carbondioxide as well as a lambda probe for the determination of oxygen areprovided for.

Furthermore, this invention covers a method for coal carbonization inwhich the afore-mentioned coke oven is implemented in one of thedisclosed embodiments, wherein

-   -   the oven is charged with coal and wherein the cokemaking process        is started,    -   the concentration of one or more gas constituent(s) is analyzed        during carbonization,    -   this data are transmitted to a computer unit,    -   this computer unit determines the supply of primary and/or        secondary air on the basis of stored discrete values or model        computations, and    -   this computer unit activates the control elements of the shutoff        devices for primary and/or secondary air via control lines, and        thus    -   it regulates the primary and/or secondary air.

In an improved variant of this method,

-   -   the temperature in the coke oven sole and/or waste gas channel        is determined, and    -   this data is transmitted to a computer unit, and    -   subsequently this computer unit determines the supply of primary        and/or secondary air on the basis of stored discrete values or        model computations, and    -   the control elements of the shutoff devices for primary and/or        secondary air are controlled via control lines, and thus    -   the primary and/or secondary air is controlled and regulated        during coal carbonization.

The method embodying this invention is applied in such a manner thatduring coal carbonization the mean temperature in the coke oven solefalls by 350° C. to 400° C. and does not fall under 1000° C.Furthermore, an optimization resides in controlling and regulating theoxygen concentration in the waste gas channel at a constant level withina range of 7.5 to 8.5 percent by volume.

The invention is described by taking an example based upon the variantof the embodiment shown in FIG. 1, with the invention not beingrestricted to the example of this embodiment. FIG. 1 illustrates a cokeoven consisting of a coke oven chamber 1 and a coke oven sole 2, whereinthe individual chambers or channels of the coke oven sole 2 are notillustrated. Via gas channel 3 the coke oven chamber 1 is connected tothe coke oven sole 2. Primary air can be supplied through line 4 intothe coke oven chamber 1, with a control flap 7 being arranged in theline 4. Secondary air can be supplied through line 5 into the coke ovensole 2, with a control flap 8 being arranged in the line 5. Line 9serves for taking a small gas volume stream from coke oven chamber 1 andconnects coke oven chamber 1 with an analyzer 10 which in theillustrated example is suitable for H₂ measurement. The gas to bemeasured and conveyed in line 9 is aspirated by means of compressor 11and conveyed to the analyzer 10. A heat exchanger 12 is installedupstream to compressor 11 to cool the gas. Via line 21, the gas volumestream is passed back into the coke oven chamber 1.

Furthermore, the temperature measuring device 13 arranged in the cokeoven sole 2 and the lambda probe 14 arranged in the waste gas channel 6are schematically illustrated. Via the data buses 17 and 18, themeasured values are transmitted to the computer unit 16 which alsoreceives the measured values from the analyser 10 via data bus 15. Viacontrol lines 19, the computer unit 16 controls the control flap 7 andthus regulates the volume stream of primary air and, respectively, thetemperature in the coke oven chamber 1. Furthermore, the computer unit16 controls the control flap 8 via the control line 20, therebyregulating the volume stream of secondary air and, thus, the temperaturein the coke oven sole 2 as well as the content of oxygen in the wastegas channel 6.

By applying the method described hereinabove and the device embodyingthis invention, it was managed to reduce the coking time substantially.Now it is possible to reliably achieve a coking time of less than 48hours, which represents a remarkable increase in oven performance rateas compared with the state of the art in technology.

LIST OF REFERENCE NUMBERS

-   1 Coke oven chamber-   2 Coke oven sole-   3 Gas channel-   4 Line (primary air)-   5 Line (secondary air)-   6 Waste gas channel-   7 Shutoff element (primary air)-   8 Shutoff element (secondary air)-   9 Line-   10 Analyzer-   11 Compressor-   12 Heat exchanger-   13 Temperature measuring instrument-   14 Lambda probe-   15 Data bus-   16 Computer unit-   17 Data bus-   18 Data bus-   19 Data bus-   20 Data bus

1-10. (canceled)
 11. A coke oven built in flat-type constructionconsisting of a coke oven chamber and a coke oven sole consisting ofchannels, with the coke oven chamber and coke oven sole being connectedto each other via gas channels, and wherein one or several openingport(s) or channel(s) for supplying primary air and one or more openingport(s) or channel(s) for supplying secondary air into the coke ovensole are provided for in the oven wall and/or oven door, and whereinshutoff devices are arranged in front of these opening ports or in thelines conducing to these opening ports, wherein the coke oven isconnected with at least one measuring device to measure theconcentration of gas constituents of the coke oven chamber, coke ovensole and/or waste gas channel, and this measuring device in turn islinked to a computer unit in such a way that this computer unit canreceive data and measured results from the measuring device, and thiscomputer unit is connected via control lines to one or more adjustingdevice(s) of said shutoff devices.
 12. The coke oven according to claim11, wherein a temperature measuring device is arranged in the coke ovensole or in the waste gas channel, said temperature measuring device alsobeing connected to the computer unit in such a way that it can receivedata and measured results from the temperature measuring device.
 13. Thecoke oven according to claim 11, wherein the measuring device is ananalyzer for the determination of hydrogen, nitrogen, carbon monoxide orcarbon dioxide.
 14. The coke oven according to claim 13, wherein theanalyzer is linked via a line to the coke oven chamber.
 15. The cokeoven according to claim 11, wherein the measuring device is a lambdaprobe for the determination of oxygen and arranged in the coke oven soleor in the waste gas channel.
 16. The coke oven according to claim 13,wherein an analyzer for the determination of hydrogen, nitrogen, carbonmonoxide or carbon dioxide as well as a lambda probe for thedetermination of oxygen are provided for.
 17. A method for coalcarbonization, utilizing a coke oven according to claim 1, comprising:charging said oven with coal and the cokemaking process being started,analyzing the concentration of one or more gas constituent(s) duringcarbonization, transmitting this data to a computer unit, determiningthe supply of primary and/or secondary air with the computer unit on thebasis of stored discrete values or model computations, and the computerthus activating the control elements of said shutoff devices for primaryand/or secondary air via control lines, thus regulating the primaryand/or secondary air.
 18. The method for coal carbonization according toclaim 17, comprising determining the temperature in the coke oven soleand/or waste gas channel, and transmitting this data to a computer unit,determining the supply of primary and/or secondary air by this computerunit on the basis of stored discrete values or model computations, andthe computer thus activating the control elements of the shutoff devicesfor primary and/or secondary air via control lines, thus regulating theprimary and/or secondary air during coal carbonization.
 19. The methodfor coal carbonization according to claim 17, wherein the meantemperature in the coke oven sole during coal carbonization falls by350° C. to 400° C. and does not fall under 1000° C.
 20. The method forcoal carbonization according to claim 17, wherein the concentration ofoxygen in the waste gas channel constantly lies in the range of 7.5 to8.5 percent by volume.
 21. The coke oven according to claim 11, whereinthe oven is a non-recovery and/or heat recovery coke oven.
 22. The cokeoven according to claim 11, wherein the shut off devices comprisesvalues, flaps or slide gates.